Techniques for calibrating wireless power transmission systems for operation in multipath wireless power delivery environments
The technology described herein relates to techniques for calibrating wireless power transmission systems for operation in multipath wireless power delivery environments. In an implementation, a method of calibrating a wireless power transmission system for operation in a multipath environment is disclosed. The method includes characterizing a receive path from a calibration antennae element to a first antennae element of a plurality of antennae elements of the wireless power transmission system, characterizing a transmit path from the first antennae element to the calibration antennae element, and comparing the transmit path to the receive path to determine a calibration value for the first antennae element in the multipath environment.
1. A system for calibrating a radio frequency (RF) transceiver, the system comprising:
a plurality of antennas including a test antenna element (AE); and
a controller operatively coupled to the test AE, wherein the controller is configured to:
determine a phase at which a first RF signal was received by the test AE from at least one calibration antenna;
direct the test AE to transmit, at two or more different sequential phase settings, a second RF signal to the at least one calibration antenna; and
identify, for subsequent use by one or more of the plurality of antennas in transmitting an additional RF signal directed to a location of an RF receiver device, a phase of the two or more different sequential phase settings corresponding to a maximum peak power that the second RF signal was received by the at least one calibration antenna.
2. The system of claim 1 , wherein:
the plurality of antennas further includes a reference AE operatively coupled to the controller; and
the controller is further configured to determine a phase at which the first RF signal was received by the reference AE from the at least one calibration antenna.
3. The system of claim 2 , wherein the controller is further configured to direct the RF transceiver to transmit, to the at least one calibration antenna, data representative of the determined phase at which the first RF signal was received by the reference AE from the at least one calibration antenna.
4. The system of claim 2 , wherein the controller is further configured to:
compute a reference phase by subtracting a reference path delay phase from the determined phase at which the first RF signal was received by the reference AE from the at least one calibration antenna; and
direct the reference AE to continuously transmit a third RF signal at the reference phase to the at least one calibration antenna.
5. The system of claim 1 further comprising the at least one calibration antenna operatively coupled to the controller.
6. The system of claim 5 , wherein the plurality of antennas include an antenna array operatively coupled to the controller, and wherein the at least one calibration antenna is further positioned apart from, and in a near field with respect to, the antenna array.
7. A method for calibrating a radio frequency (RF) transceiver having a plurality of antennas including a test antenna element (AE), the method comprising:
determining a phase at which a first RF signal was received by the test AE from at least one calibration antenna;
directing the test AE to transmit, at two or more different sequential phase settings, a second RF signal to the at least one calibration antenna; and
identifying, for subsequent use by one or more of the plurality of antennas in transmitting an additional RF signal directed to a location of an RF receiver device, a phase of the two or more different sequential phase settings corresponding to a maximum peak power that the second RF signal was received by the at least one calibration antenna.
8. The method of claim 7 , wherein the plurality of antennas of the RF transceiver further includes a reference AE, the method further comprising determining a phase at which the first RF signal was received by the reference AE from the at least one calibration antenna.
9. The method of claim 8 further comprising directing the RF transceiver to transmit, to the at least one calibration antenna, data representative of the determined phase at which the first RF signal was received by the reference AE from the at least one calibration antenna.
10. The method of claim 8 further comprising directing the reference AE to continuously transmit a third RF signal at a reference phase to the at least one calibration antenna.
11. The method of claim 10 further comprising computing the reference phase by subtracting a reference path delay phase from the determined phase at which the first RF signal was received by the reference AE.
12. The method of claim 7 further comprising calculating a calibration value for the test AE according to a difference between the determined phase at which the first RF signal was received by the test AE and the identified phase of the two or more different sequential phase settings corresponding to the maximum peak power.
13. The method of claim 12 further comprising adjusting, based on the calibration value, a phase of the test AE prior to the RF transceiver transmitting the additional RF signal directed to the location of the RF receiver device.
14. The method of claim 13 , wherein adjusting the phase of the test AE comprises adding the calibration value to the determined phase at which the first RF signal was received by the test AE.
15. The method of claim 7 further comprising receiving, from the at least one calibration antenna, data representative of a received signal strength at which the second signal was received by the at least one calibration antenna at each of the two or more different sequential phase settings.
16. The method of claim 15 , wherein identifying the phase of the two or more different sequential phase settings corresponding to a maximum peak power comprises identifying the phase according to the data representative of the received signal strength.
17. The method of claim 7 , wherein the test AE receives the first RF signal from the at least one calibration antenna, and the second RF signal is transmitted at the sequential phase settings from the test AE to the at least one calibration antenna along a plurality of paths, or reflected off one or more objects, in a multipath environment.
18. The method of claim 7 further comprising:
detecting a system startup process of the RF transceiver; and
performing the determining, directing and identifying steps in response to detecting the system startup process.
19. The method of claim 7 further comprising iterating through the steps of the method for another test AE of the plurality of antennas of the RF transceiver.
20. One or more non-transitory computer readable media having program instructions stored thereon which, when executed by at least one processor of a radio frequency (RF) transceiver having a plurality of antennas including a test antenna element (AE), cause the RF transceiver to:
determine a phase at which a first RF signal was received by the test AE from at least one calibration antenna;
direct the test AE to transmit, at two or more different sequential phase settings, a second RF signal to the at least one calibration antenna; and
identify, for subsequent use by one or more of the plurality of antennas in transmitting an additional RF signal directed to a location of an RF receiver device, a phase of the two or more different sequential phase settings corresponding to a maximum peak power that the second RF signal was received by the at least one calibration antenna.